The present invention relates to adhesives and sealants based on specific binders comprising at least 0.32% by weight of 2-ethylhexyl methyl terephthalate, based on the overall adhesive or sealant. In addition, the invention discloses a process for preparing them, and their use.
Adhesives and sealants based on polyurethanes, polyureas, polyacrylates, polysulphides, silylated polyurethanes, silylated polyureas, silylated polyethers, silylated polysulphides and silyl-terminated acrylates have a very broad application spectrum and are used, in formulations adapted to the particular end use, in—for example—construction and civil engineering, in the aircraft or automotive industry, and in watercraft construction. A key component of such a formulation is generally plasticizers, which may account for a fraction of more than 40% of the total formulation. Plasticizers, according to DIN 55945, are inert organic solids and liquids with a low vapour pressure. Through their solvency and swelling capacity, they reduce the hardness of the polymer, compatibilize the filler/polymer mixture, and raise the low-temperature elasticity. Plasticizers in adhesives and sealants also serve in particular to increase the expandability of the film that is produced.
Adhesives and sealants are intended to be very easy to process, but also to be sufficiently sag-resistant; in other words, the plasticizer used is intended as far as possible to lower the force required for processing, on ejection of the sealant from the cartridge, for example, but at the same time not to cause sustained impairment of the sag resistance. This property is determined through the flow point. Moreover, adhesives and sealants are intended, after crosslinking, to obtain an optimum balance between elongation and tensile strength, and, after having been introduced into the joint or the substrate, should be optimally amenable to smoothing.
Given that the stated compounds and methods have still not ultimately solved the fundamental problem of optimizing the properties of adhesives and sealants based on polyurethanes, polyureas, polyacrylates, polysulphides, silylated polyurethanes, silylated polyureas, silylated polyethers, silylated polysulphides and silyl-terminated acrylates, the object on which the present invention is based was that of developing other formulations, which are easy to process, based on these polymers. In such formulations, the adhesives and sealants should have a low flow point and also good mechanical properties, and in addition ought to result in optimal smoothness.